The present invention relates to a vehicle suspension, and more particularly to a steerable independent suspension system which includes at least one cross member to reduce side loads, and increase roll stiffness.
The use of leaf spring suspension systems for cushioning a front steering axle is well known in the art. The use of air suspension systems in connection with the rear axles of vehicles is also well known. Attempts to adapt such air suspension systems to a front steering axle have been difficult because of concerns regarding bending loads and vehicle roll stability.
Vehicle suspensions are subjected to heavy bending loads through impacts and vibrations caused by bumps in the roadway, wheel offset, braking and other such loads. Bending loads and roll stability are of particular concern for vehicles which carry a load having a high center of gravity.
Air spring suspension systems include bellows-shaped air spring elements which are adjustable to compensate for various vehicle load conditions. However, air springs are rather unstable in certain vehicle roll restraining respects. Rigid axle housings have been used for torsional stability, but are necessarily inapplicable to an independent suspension system. Other mechanical torsional restrictors are also inapplicable because of the limited space allocated in the vehicle front end where many rather large vehicle components such as the engine and radiator are typically located.
Accordingly, it is desirable to provide an independent steerable air suspension system for a vehicle which provides enhanced roll stability while not interfering with components located in the vehicle forward section.
The independent steerable air suspension system according to the present invention generally includes a torsional member to interconnect independent longitudinally extending suspension arms. The torsional member ties together the suspension arms and provides torsional resistance therebetween. Bending moment due to the wheel load offset and other braking and side loads are transmitted through the hanger brackets and the torsional member. Roll stiffness is thereby increased and vehicle handling is improved.
In another embodiment, a lateral support member is located adjacent the air springs. By locating the lateral support member adjacent the air springs, a substantially rigid U-shaped system is constructed which resists bending loads and provides enhanced roll stability.
In another embodiment, the suspension system includes both a torsional member and a lateral support member to provide a rigid square-shaped suspension system to resist bending loads and provide still further roll stability.